Don't forget about "Turbo Boost" - that "1.8 GHz" runs at 2.8 GHz when you're only using one of two cores.

Combined with a more efficient architecture, this helps explain the performance gains.

That's because the boards are getting more cycles in GPU and cache and things, which are more important than straightahead serial speed.

Yes, I'm well aware of the reasons why my computers get faster even at lower clock speeds. I think of the megahertz myth, I picture clock speeds staying the same and getting more done at those clock speeds (e.g., all my computers would forever be pegged at 2 GHz but would continue to get faster). It was only today that I realized that clock speeds (at least in my case) are going down (rather than staying constant) while computation ability and battery life continue to increase.

It's also because the power consumption is quadratic with the frequency. This is important if you agree that an additional hour on battery is worth much more than few cylces per sec.

No, the first-order model is that power consumption is quadratic with voltage, and linear with frequency.

Ok, but isn’t increasing the voltage required to keep the transistors stable as you increase the frequency ?

That's kind of irrelevant anyways, all modern CPU's have speed stepping functionality that can reduce the clock speed while on battery.

That's why your cpu runs on different paths to save power when not needed. Using a lower cpu is just lazy and cheap.

Agreed, but I think the point is that while the growth curve may indeed be 'bending down', for non-upgradeable components like cache memory, memory controllers, GPUs, AND CPUs, the growth curve certainly hasn't leveled out.